All Physics Faculty Publications

Document Type

Article

Journal/Book Title/Conference

Physical Review B

Volume

66

Issue

16

Publication Date

10-29-2002

First Page

165217

Last Page

165228

DOI

10.1103/PhysRevB.66.165217

Abstract

We have studied the ultrafast optical response of native-oxide terminated Si(001) with pump-probe reflectivity using 800 nm, 28 fs pulses at an excitation density of (5.5±0.3)×1018cm-3. Time-dependent reflectivity changes comprise third-order-response coherent-transient variations arising from anisotropic state filling and linear-response variations arising from excited free carriers, state filling, and lattice heating. A time constant of 32±5fs associated with momentum relaxation is extracted from the coherent-transient variations. The state-filling and free-carrier responses are sensitive to carrier temperature, allowing an electron-phonon energy relaxation time of 260±30fs to be measured. The recovery of the reflectivity signal back towards its initial value is largely governed surface recombination: a surface recombination velocity of (3±1)×104cm s-1 is deduced for native-oxide terminated Si(001).

Comments

Published by American Physical Society in Physical Review B. Publisher PDF is available for download through link above.